Causes of Fuel Pump Failure and Signs to Identify a Failing Fuel Pump
12v fuel pump is one of the most important components in a vehicle's fuel delivery system. If it is doing well, fuel delivery system functions normally. But, once it fails, the car engine ceases to run. However, the failure and the inconvenience it causes can be prevented by identifying the early warning signs.
In this article, we will discuss the common causes of fuel pump failure and its warning signs.
Causes of failure: There are more than a couple of causes for its failure. They are as follows:
• Broken wiring: Broken or faulty wiring in the vehicle's fuel system prevents the current flow to the fuel pump from the relay. Even the corroded, loose, melted or burnt wires/connectors, and poor electrical grounding can restrict the current or voltage flow from the relay to the fuel pump, thus, affecting its functioning - pumping fuel to the engine.
• Problems in the fuel tank: Presence of dust/debris, rust or dirty fuel in tank can result in its malfunctioning. During cool and humid weather, when the tank is low, it gets moist leading to the oxidation of the tank and formation of rust. As it is located inside the tank, the rust will be ingested in to the fuel pump, bringing about its failure.
• Clogged fuel filter: Usage of dirty fuel or presence of contaminants in the tank can clog the pickup strainer or filters present in the fuel lines. This results in low pressure and low peak flow of fuel that weaken its functioning.
Clogged filters are generally associated with damaged fuel line connectors/splits or cracked hoses or kinked fuel lines that lead to leakage of fuel. These cracks or leaks on the fuel lines can create vacuum leaks, which disturb the air-fuel ratio, thus, making the engine run lean.
• Driving with low fuel level: Its durability depends on the lubrication and the cooling provided by the fuel. Running your vehicle on a low gas tank frequently, may heat up the fuel tank much quicker, ultimately overheating the fuel pump. As a result, due to the lack of lubrication, it becomes dry and gets damaged.
Identifying a bad fuel pump: It shows many warning signs, which when identified at the right time, will avoid complete damage. A few warning signs are quite clearly evident if thoroughly checked - broken hoses, fuel leaks, discolored electrical terminals, burnt or bubbled plastic at the fuse, etc.
There are a few other warning signs that are displayed by the vehicle itself. They are as follows:
• Strange whining sounds: One of the early as well as the clear signs of failing fuel pump is the development of a high pitched screeching sound, when the engine is first engaged. However, the sound will slowly disappear after some time. Moreover, the sound is not the same for every vehicle. It may vary based on the type. An early inspection, after the development of such strange sounds will help save it from further damage.
• Engine misfires: A failing fuel pump may cause engine misfires that in turn will cause the car to jerk occasionally. Engine misfires may happen quite often, most probably 3-4 times, and later the vehicle may run smoothly for many miles. This sign translates to the wearing out of the fuel pump, because it is unable to maintain a steady fuel pressure.
• Problem in starting and accelerating: A failing or dead fuel pump may also prevent the engine from starting. If you are sure that the starter and the battery of your vehicle are good, and still you are facing a starting problem, then it is the sign of faulty relay. As already stated, faulty wiring harness can result in improper power supply to the fuel pump, thus, resulting in sluggish acceleration and starting troubles.
• Extended engine cranking time: In order to cool down the components of the fuel tank, maximum amount of fuel sent to the engine will be returned to the fuel tank. An anti-drain back valve in the outlet aids in this fuel returning process. Whenever the fuel pump stops functioning, the valve gets closed preventing the fuel from running back into the fuel tank. This condition can be identified by the extended cranking time while starting the vehicle.
• Engine loses power: This sign of engine losing power can be typically seen when the vehicle is running at high speeds, especially when climbing hills. If you are sure that there is nothing wrong with the fuel filter, it is safe to assume that it is failing.
On identifying the above issues in your fuel delivery system, it is better advised to get your vehicle checked by a good technician, who will further diagnose the issues by conducting fuel pressure and volume tests (through fuel pressure gauge), and the electrical checks (through digital volt & ohm meter). It is only after these tests, should you decide as to replace or fix your fuel pump.
Timely repairs or replacement will help you to solve the issues quickly. However, while replacing the fuel pump it is always better to opt for the best quality aftermarket products, offered by reputed dealers, to get more durable and better performing products.
Fuel Pump and Injection Repairs
The fuel pump and injector are vital to keeping your car running well. If your fuel pump and injector don't operate properly then you will issues with driving and emission. A fuel pump that is simply weak during operation will cause issues with the calibration of your fuel system. As a result you will have problems such as hard starting, poor idle quality, hesitation or stumbling when you accelerate and a loss in the high speed power of your vehicle.
Electric fuel pumps will experience problems with wear after many years of continuous service. Gradual loss of pressure and flow can result from the wear on pump vanes, rollers or gears. If the inlet filter sock lets sediment or rust get by then you will also have accelerated wear. This can even cause serious problems such as overheat and burn out if the pump becomes jammed with the sediment. Lubrication and cooling of the fuel pump only occurs when fuel is passing through it.
If you start having problems with your fuel pump then the first thing you should do is check the voltage supply and the electrical connections. You may simply just need to replace a fuse or loose wire. However, if everything is fine then you will need to run a measuring static output pressure and fuel delivery test to check the ability of the pump to deliver fuel. If your pump is not meeting manufacturer's requirements after these test then you will need to replace the entire fuel pump.
When replacing your fuel pump always remember to disconnect the battery to prevent unwanted sparks during the replacement process. And always remember to drain the tank first. Before putting in a new fuel pump it is always a good idea to also replace the filter screen and use new o-ring and gaskets.